1. Field of the Invention
The present invention relates to a fuel supply system for a motorcycle. More particularly to a fuel supply system having a space-saving design in regard of installation space thereof.
2. Description of Background Art
A supply system for a motorcycle is known wherein a fuel filter device is disposed on the downstream side of a fuel pump unit. See, for example, Japanese Patent Laid-open No. 2008-248753 (FIGS. 1 to 3). The fuel supply system shown in Japanese Patent Laid-open No. 2008-248753 (FIGS. 1 to 3) has a configuration in which while the fuel pump unit is provided inside a fuel tank, the fuel filter device is disposed on the rear side of a throttle body and on the upper side of a crankcase, and is mounted through a bracket to a center frame extending vertically on the rear side of a power unit.
On the other hand, a system in which, due to a restriction imposed by a fuel tank or the like, a fuel pump unit is disposed on the upper side of an output shaft in a crankcase of a power unit and on the front side of a rear shock absorber is shown in Japanese Patent Laid-open No. 2005-096504 (FIGS. 1 and 2).
A fuel supply system for a motorcycle having a fuel filter device on the downstream side of a fuel pump unit as shown in Japanese Patent Laid-open No. 2008-248753 has a problem in that when it is intended to arrange the fuel pump unit outside the fuel tank as in Japanese Patent Laid-open No. 2005-096504 (FIGS. 1 and 2), it is difficult to secure the arrangement space required.
Particularly, in the case of a motorcycle using a gasoline-ethanol mix fuel as described in Japanese Patent Laid-open No. 2008-248753, it is highly necessary to provide a fuel filter device on the downstream side of the fuel pump unit for the purpose of removing the dust present in ethanol. In that case, also, there has been a demand for a fuel supply system having a space-saving configuration in which a fuel pump unit can be disposed outside a fuel tank.